SAN FRANCISCO - By all rights, Twitter should be wildly popular with mainstream America. World leaders, the pope, even Justin Bieber post updates there. It tells us what's culturally relevant at any given moment, be it Beyonce's performance at the Super Bowl and the blackout in the New Orleans Superdome or Syfy channel's campy made-for-TV movie "Sharknado" about a tornado teeming with sharks. But Twitter doesn't have nearly the following most people think it has. Twitter will reveal for the first time in a year how many users it has when it makes public its stealth filing for an initial public offering as soon as this week.

The director and some cast members of "Sharknado 2: The Second One" appeared on stage in a Pasadena hotel on Tuesday to preview the upcoming airborne shark sequel and touched on a very serious topic: climate change. Whoever could have predicted that Ian Ziering taking on flying sharks with a chain saw would give Al Gore a run for his cinematic money? Costar Judah Friedlander, the guy who always wore trucker caps on "30 Rock," plays a childhood friend of Ziering's character and proclaimed the film about a weather phenomenon involving flying sharks "the most important ever made about climate change.

Starz has given the greenlight to "Outlander," a new series set in 18th century Scotland and based on the bestselling series of books by Diana Gabaldon. The series follows Claire Randall, a 20th century doctor who travels in time back to Scotland in the 1740s where she is forced to marry a young Scottish warrior. The seven-book series has been described as a mix of romance, adventure, history and science fiction. The TV adaptation is being overseen by writer and executive producer Ronald D. Moore, best known for his work reinvigorating "Battlestar Galactica" on SyFy.

Customized TV Listings are available here: www.latimes.com/tvtimes Click here to download TV listings for the week of August 25 - 31, 2013 in PDF format This week's TV Movies SERIES Cracked The Canadian police drama premieres with two new episodes. 7 and 9; 8 and 10 p.m. REELZ Ghost Adventures In this new episode, Nick, Zak and Aaron visit the abandoned Tuolumne Hospital in Sonara, Calif. 9 p.m. Travel Alaskan Steel Men This new unscripted dangerous profession series revolves around the maintenance and repair crews who keep Kodiak's fishing fleet afloat.

"Haven," a new series premiering Friday on Syfy, is like the Syfy series "Eureka" in that it concerns a small piney town populated by the abnormally gifted. And it is like the Syfy series "Warehouse 13" in that it is like "The X-Files," setting two good-looking officers of the law — male and female, local cop and federal agent — against otherworldly phenomena. She is open to the supernatural; he has a condition that makes it impossible for him to feel pain. She's an orphan, he has father issues.

"Sharknado. " It's on everyone's lips and Twitter feeds. "Sharknado. " The drive-in-quality TV movie starring Ian Ziering and Tara Reid aired on Syfy on Thursday night and somehow, miraculously, it managed to capture the national zeitgeist. Hollywood was a-Twitter about it. RELATED: 'Sharknado' creates a social media storm But anyone arriving late to the "Sharknado" party may be surprised/shocked/appalled to learn that the film, about a tornado of sharks terrorizing the citizens of Los Angeles, doesn't represent Syfy's first dive into these waters.